398 i B. fYRRELL — POST-TERTIAR"* DEPOSITS OF MANITOBA. 



gradually disappear on proceeding eastward those of gneiss become more 

 numerous, and pebbles of Paleozoic limestone also become very common. 



In thickness the till varies greatly in different places, ranging down from 

 500 feel or more to a very thin covering; but, generally Bpeaking, throwing 



oul of account deposits clearly referable to terminal moraines, it be< ies 



slightly thinner from cast to west, the outcrops seen along the 3,000 fool 

 contour line above mentioned being as a rule not more than a few feet in 

 thickm - 



Throughout the greater portion of the area under consideration the till 

 falls naturally into two major subdivisions, a lower very compact bluish- 

 gray unstratified deposit, and an upper softer and sometimes thickly lamel- 

 lated clay usually of a light brownish color. These two subdivisions have 

 been chiefly recognized in the extreme western portion of the area, from the 

 international boundary north to the North-Saskatchewan river, where they 

 are often separated by stratified waterlaid deposits, in which, on the Belly 

 river. Dr. Dawson records the occurrence of a bed of lignite eight inches in 

 thickness. The till in this latter locality is also of extraordinary thickness 

 as compared with the average found farther north between the How and 

 North-Saskatchewan rivers. Farther easl these two subdivisions have not 

 been so generally recognized, probably on account of the great thickm -- 

 of the whole deposit and the comparative paucity of g I sections. 



Terminal Moraines. -Intimately associated with the till are a number of 

 irregular ridges of rounded hill< severed by deep depressions, in the bottoms 

 of which are often lakelets of char, sweet water without visible outlets 



'The rim of the basin of oi f these lake- i- frequently fifty or sixiv feel 



above the surface of the water, and surrounding knolls in many cases rise to 

 a height of from a hundred to a hundred and fifty feet higher. Sections of 

 these hills Bhow them to be masses of transported material, consisting of un- 

 stratified sand, clay, and bowlders, and their Bides and summits are almost 

 always thickly strewn with large northern or eastern erratic-. 



A - to the mode of formation of these hilly tracts, t here is now little room 

 for doubt that they were the terminal moraines of one or more extensive 

 glaciers that moved outward- from the central Archean nucleus, planing off 

 the higher point- of the surface and shoving before them the accumulated 

 mass of mixed material. Much of this fell hack under the moving ice in 

 the depressions of the preglacial Burface, while the rest, consisting chiefly of 

 the coarser material, continued at the ice-foot, and was left as an irregular 

 ridge on the final retreat of the -lacier. Very few of these morainic belts 

 have as y< i been definitely located, but the following may be mentioned 

 some that have I,. m examined in late y< ars and whose character is pretty 



ainl v know n. 



< >n the western margin of the Winnipeg basin, a rugged morainic ridge 



